Structures of transient species in the photochromic reaction of 1′,3′,3′-trimethylspiro[2H-1-benzopyran-2,2′-indoline]: Time-resolved resonance Raman study of isotopically substituted analogues
摘要:
Time-resolved resonance Raman spectra of seven kinds of isotopically substituted analogues of 1,'3',3'-trimethylspiro[2H-1-benzopyran-2,2'-indoline] in the photomerocyanine form have disclosed that only the vibrations of the cleaved benzopyran part are resonance enhanced significantly in cyclohexane and in acetonitrile solutions with 460-390 nm probe light. Dramatic changes in the resonance Raman spectra of the photomerocyanine on going from non-hydrogen-bond donor solvents to hydrogen-bond donor solvents can be interpreted as being due to changes in the relative contribution of ortho-quinoidal and zwitterionic forms in the resonance hybrid structure of the photomerocyanine: in cyclohexane and in acetonitrile the contribution of the ortho-quinoidal form is substantial, while in methanol the zwitterionic form is stabilized by hydrogen bonding with the solvent and the photomerocyanine takes an almost zwitterionic structure.
The first general route for efficient synthesis of 18O labelled alcohols using the HOF·CH3CN complex
作者:Julia Gatenyo、Inna Vints、Shlomo Rozen
DOI:10.1039/c3cc42337a
日期:——
A mild and very efficient method for converting boronic acids to alcohols has been developed using the acetonitrile complex of hypofluorousacid HOF.CH3CN. Employing (18)O-labeled water results in alcohols containing a heavy oxygen isotope. The reactions were performed at room temperature, within a few minutes and in excellent yields.
Oxygenation of Organoboronic Acids by a Nonheme Iron(II) Complex: Mimicking Boronic Acid Monooxygenase Activity
作者:Sayanti Chatterjee、Tapan Kanti Paine
DOI:10.1021/acs.inorgchem.5b01198
日期:2015.10.19
decarboxylation of an iron(II)–benzilate complex [(TpPh2)FeII(benzilate)] (TpPh2 = hydrotris(3,5-diphenyl-pyrazol-1-yl)borate), toward organoboronic acids. The oxidant converts different aryl/alkylboronic acids to the corresponding oxygenated products with the incorporation of one oxygen atom from dioxygen. This method represents an efficient protocol for the oxygenation of boronic acids with dioxygen as the terminal
作者:Xiao Shen、Constanze N. Neumann、Claudia Kleinlein、Nathaniel W. Goldberg、Tobias Ritter
DOI:10.1002/anie.201500902
日期:2015.5.4
An alkylaryletherbondformation reaction between phenols and primary and secondary alcohols with PhenoFluor has been developed. The reaction features a broad substrate scope and tolerates many functional groups, and substrates that are challenging for more conventional etherbond forming processes may be coupled. A preliminary mechanistic study indicates reactivity distinct from conventional ether
Mechanically induced solvent-free esterification method at room temperature
作者:Lei Zheng、Chen Sun、Wenhao Xu、Alexandr V. Dushkin、Nikolay Polyakov、Weike Su、Jingbo Yu
DOI:10.1039/d0ra09437d
日期:——
Herein, we describe two novel strategies for the synthesis of esters, as achieved under high-speed ball-milling (HSBM) conditions at room temperature. In the presence of I2 and KH2PO2, the reactions afford the desired esterification derivatives in 45% to 91% yields within 20 min of grinding. Meanwhile, using KI and P(OEt)3, esterification products can be obtained in 24% to 85% yields after 60 min of
A visible‐light‐promoted aerobicoxidativehydroxylation of boronic acidsusing phthalocyanine zinc as an easily available photosensitizer has been developed. It provided a direct access to synthesize aliphatic alcohols and phenols from boronic acids. The advantages of this approach included the low catalyst loading (0.5 mol%), high efficient, the use of O2 as an oxygen source, wide substrate range